The prior art has taught a wide variety of processes for producing snack food products and products made by a number of these processes are currently available to the consumer. Typically, many of these products are deep fat fried to give the product an expanded configuration. However, the fat fried products of the art have the disadvantages of absorbing too much fat on frying as well as containing substantial amounts of carbohydrates, resulting in a product which has a high energy content and which is not acceptable to consumers who want a low calorie snack product. To avoid the problem of high fat content, it has been suggested that snack products be formed from a dough containing a low fat content and cooked by high temperature oven drying or by exposure to microwave or infrared radiation rather than frying. These methods do avoid the problem of high fat content in the product, but fail to produce the high palatability which is developed in the frying process.
It has also been suggested that in order to reduce the calories of snack products, protein alone, e.g., soybeans, be used in cooked form to make a snack-type wafer. However, it was found that, as for example in U.S. Pat. No. 3,911,142, there was insufficient starch or other binder to cohere the particles, thus causing crumbling, generally poor structural integrity and a less than desirable mouth feel. If additional water was added, then the raw mass became sticky and unmachineable during processing.
U.S. Pat. No. 3,244,538 describes a process for reducing the fat content of fried foods which involves first drying the food, then cooling it. Generally, the process leads to case hardening or formation of a hard outer shell which prevents loss of moisture from the core of the product and reduces fat absorption from the outside. This product is useful in french frying potatoes or in making potato chips. However, in making a high protein snack product a case hardened exterior and moist interior is fatal because the texture and mouth feed are undesirable, plus the capability of the product to puff or expand is adversely affected.